Peptide Hormones
- Binding Site
- Site of Synthesis
- Hydrophobicity/ Hydrophilicity
- Storage
- General Functions
- Long/ Short Lasting Effects?
- Bind external receptors on the cell surface
- Synthesized in the ER and modified in the Golgi
- Hydrophilic (when in the bloodstream, can dissolve within the plasma)
- Can’t cross biological membranes without specific transport mechanisms
- Stored in vesicles
- Large products
- Communicate with the cell interior via secondary messenger systems (catalytically activated by binding)
- -> Leads to signal amplification, which alter the activity of enzymes within the cytoplasm.
- Short lasting effects
Steroid Hormones
- Binding Site
- Site of Synthesis
- Hydrophobicity/ Hydrophilicity
- Storage
- General Functions
- Long/ Short Lasting Effects?
- Synthesized from cholesterol in the SER.
- Highly hydrophobic, so steroid hormones can enter biological membranes passively.
- Thus, steroid hormones are not stored, but are synthesized as they are needed.
- Small products
- Steroid hormones travel in the blood stream attached to carrier proteins (such as albumin).
- Steroids diffuse into the cell in which they enter the nucleus and increase the transcription of genes in the nucleus.
- Much slower effects
What is an endocrine gland?
–A ductless gland whose secretory products are picked up by capillaries supplying blood to the region.
What is an exocrine gland?
–Secrete their products into the external environment by ways of ducts, which empty into the GI lumen or the external world.
What is a tropic hormone?
- Hormones which regulate the release of other hormones.
- -> Ex. ACTH released from the anterior pituitary acts on the adrenal cortex to release cortisol.
What is negative feedback?
When the increased product of one hormone inhibits the production of substrates earlier in the pathway.
Which are the 2 portal systems vital to circulating hormones in the body?
- Hypothalamic- Pituitary Portal System
2. Hepatic Portal System
Thyroid Hormone
- Produced from the amino acid tyrosine in the thyroid gland
- Comes in 2 forms (T3 and T4)
- Produced from Thyroid Stimulating Hormone (TSH) from the anterior pituitary, which is stimulated by Thyroid Releasing Hormone (TRH) from the hypothalamus.
- Thyroid Hormone increases metabolic rate & body temperature.
- -Although TH is an amino acid- derived hormone, it alters transcription (resembling a steroid hormone) in the nucleus.
What Hormones are released from the Anterior Pituitary?
F –> Follicle Stimulating Hormone (FSH)
L –> Luteinizing Hormone (LH)
A –> Adrenocorticotropic Hormone (ACTH)
T –> Thyroid Stimulating Hormone (TSH)
P –> Prolactin
I (ignore)
G –> Growth Hormone
What Hormones are released from the Posterior Pituitary?
Vasopressin (ADH)
Oxytocin
Name the pathway which leads to cortisol production in the adrenal cortex, starting from the hypothalamus.
The hypothalamus senses low blood cortisol, and releases Corticotropin- Releasing Hormone (CRH), which acts on the anterior pituitary to release ACTH. ACTH acts on the adrenal cortex to increase cortisol production.
Growth Hormone
Increases bone growth and increases cell turnover rate
Prolactin
-Increases mammary gland milk production
LH
Females:
Ovulation
Males:
Testes/ Testosterone Synthesis
FSH
Females:
Follicle/ Ovary Development
Males:
Testes/ Spermatogenesis
ADH / Vasopressin
Increases salt / water retention in the kidneys
increase blood volume / BP
Oxytoxin
Breast milk letdown Uterus contractions (+ feedback)
Thyroid Hormone
- Increases metabolic rate and body temperature
- Necessary for physical and mental development in children
Calcitonin
- Released from the thyroid (C cells)
- Acts on the bones and kidney’s to reduce blood calcium levels
Parathyroid Hormone (PTH)
- Released from the parathyroids
- Acts on the bone/ kidney and small intestine to raise blood calcium levels
Thymosin
- Secreted in children only
- Released from T cells during childhood
Epinephrine
- Secreted from the adrenal medulla
- Modified amino acid hormone
- Increases SNS responses (rapid)
Cortisol
- Secreted from the adrenal cortex
- Longer-term stress response
Increase blood glucose and increases protein catabolism
Reduces inflammation and immunity
Aldosterone
- Secreted from adrenal cortex
- ->Mineralcorticoid (steroid hormone)
- Acts on the kidney to increase Na/ water absorption to increase absorption.
